1. Field of the Invention
The present invention relates to a solid-state imaging device such as a CMOS image sensor or a CCD image sensor, a method of manufacturing the same, and a camera having such solid-state imaging device.
2. Description of the Related Art
Solid-state imaging devices can be roughly classified into amplifying solid-state imaging devices as represented by CMOS image sensors and charge-transfer solid-state imaging devices as represented by CCD solid-state imaging devices. When CMOS image sensors and CCD image sensors are compared, a CCD image sensor usually consumes a high driving voltage to transfer signal charge and therefore has a high power supply voltage compared to a CMOS image sensor. Accordingly, a CMOS image sensor is often used as a solid-state imaging device provided in a mobile appliance such as a camera-equipped mobile telephone or a PDA (Personal Digital Assistant) due to the power supply voltage and the power consumption being lower than with a CCD image sensor.
Japanese Unexamined Patent Application Publication No. 2006-32681 discloses the configuration of a CMOS solid-state imaging device where the light receiving portion of a pixel includes a photodiode produced by forming a p+ type semiconductor layer on an n type semiconductor layer. Japanese Unexamined Patent Application Publication No. 2007-81448 discloses a CCD solid-state imaging device where a light receiving portion of a pixel includes a photodiode produced by forming a p+ type positive charge accumulating region on an n type impurity diffused region. The publication also discloses a technology that forms an overflow barrier by epitaxial growth and ion implantation. Japanese Unexamined Patent Application Publication No. H10-116975 discloses a method of manufacturing a super junction semiconductor element with a deep pn junction where an n-type epitaxial layer is formed and then the acceleration voltage for ion implantation is continuously changed using a photoresist mask to form a p-type semiconductor region in the n-type epitaxial layer.